Forge version: 14.23.4.2755
Twilight Forest version: 3.8.689
Link to crash log: https://pastebin.com/eAyVuees

Steps to reproduce:

1. Was exploring, have killed Naga and Lich, went into a hill to do some mining then crashed. Just loading up the game crashes to desktop now.

What I expected to happen: The game not to crash

What happened instead: The game crashed

I don't quite fully understand crash logs where the error is ConcurrentModificationException, however, the stacktrace leads back to something relating to sounds. After some digging around, it could be caused by the mod Sound Filters, though this may be speculation.

Closing as the problem doesn't appear in the mod. If this still occurs, feel free to reopen this, as well as verify if another mod may be the cause.